Process for preparing amidine salts

ABSTRACT

IS PREPARED BY REACTING THE IMIDOETHER WITH AMMONIUM CHLORIDE OR AMMONIUM BROMIDE IN THE PRESENCE OF METHANOL.   WITH METHANOL IN THE PRESENCE OF A SODIUM METHOXIDE CATALYST, AND AN AMIDINE SALT HAVING THE FORMULA   IS PREPARED BY REACTING   An imidoether having the formula

United States Patent 1 Scanlon et al.

[111 3,725,456 51 Apr. 3, 1973 [s41 PROCESS FOR PREPARING AMlDINE SALTS [75] Inventors: Patricia M. Scanlon, Arlington, Mass; Elwyn R.-Young, Nashua, N.H.

[73] Assignee:, W. R. Grace 8: Co., New York,

[52] U.S. Cl. ..260/465 D, 260/45.9 R, 260/75 N, 260/465.4, 260/465.5

51 Int. Cl ..C07c 121/66 [58] Field of Search ..260/465 D [56] References Cited OTHER PUBLICATIONS Rhone-Poulenc S.A. Chemical Abstracts, Vol. 64, p.

Primary Examiner -Lewis Gotts Assistant Examiner-Dolph H. Torrence Att0meyElton Fisher et a1.

[57] ABSTRACT An imidoether having the formula (I) /OH20N CoHsCL-N CH -C=NH is prepared by reacting /CHzCN GaH CN\ CHZCN with methanol in the presence of a sodium methoxide catalyst, and an amidine salt having the formula is prepared by reacting the imidoether with ammonium chloride or ammonium bromide in the presence of methanol.

4 Claims, No Drawings PROCESS FOR PREPARING AMIDINE SALTS This is a divisionalof application Ser. No. 830,091, filed 3 June 19 69, and now U.S. Pat. No. 3,641,103.

BACKGROUND OF THE INVENTION This invention is in the field of amidine salts and imidoethers including the preparation of such compounds.

Prior art methods for preparing amidine salts are taught by US. Pat. Nos. 2,375,740 and 3,309,374 and prior art methods for preparing imidoethers are taught by Carl R. Noller, Chemistry of Organic Compounds, W. B. Saunders Co., Philadelphia, Pa., 1951, at pages 242-243;

SUMMARY OF THE INVENTION In summary, this invention is directed to an amidine salt having a formula selected from the group consisting of NI'I:

wherein X is an ion selected from the group consisting of chloride and bromide.

DESCRIPTION OF PREFERRED EMBODIMENTS In a preferred embodiment thisinvention is directed to a process for preparing an amidine salt having a formula selected from the group consisting of wherein X is an ion selected from the group consisting of chloride and bromide, comprising:

LII

and

forming a product mixture consisting essentially of the amidine salt and methanol by contacting and reacting at about 20-40C. (preferably about 2530C.) an imidoether having a formula selected from the group consisting of 0 01mm uni-4 N tall: (1 INII (NHL.

0 (ill: (EN (211;, tum)... N/

on, (1-:Nll

0 CHzCN Gama-N CH C=NII with an ammonium salt having the formula NH X,

wherein X is an ion selected from the group consisting of chloride and bromide in the presence of methanol, the mole ratio of the imidoether to the methanol being about 1:20-60 (preferably about 1:20-40); the mole ratio of the imidoether to the ammonium salt being about 111-2, and the contact time being about 20 hours (preferably about 2-15 hours);

. separating the thus formed amidine salt from the methanol (e.g., by filtration, centrifugation, or decantation and recovering the separated amidine salt.

In another preferred embodiment this invention is directed to a process for preparing an amidine salt having the formula v wherein X is an ion selected from the group consisting of chloride and bromide, comprising:

forming a product mixture consisting essentially of the amidine salt and methanol-by contacting and reacting at about 20-35C. (preferably about 25-30C.) an amidoether having the'formula with an ammonium salt having the formula NI-LX,

In another preferred embodiment this invention is directed to a process for preparing an amidoether having a formula selected from the group consisting of and Ull CN CIIZON in the presence of a catalytic quantity of an alkali metal alkoxide, the mole ratio of the nitrile to the methanol being about 1:15-30 (preferably about lzl0-40);and

. separating the imidoether from the methanol and alkali metal alkoxide (e.g., by filtration, centrifugation, or decantation the imidoether being only slightly soluble in methanol and the alkali metal alkoxide being very substantially soluble in methanol). If desired, a quantity of methanol can be evaporated from the methanol-imidoether-alkali metal alkoxide mixture, thereby to decrease the volume of methanol present to dissolve the imidoether and thereby to increase the recovery of the imidoether.

GENERAL DESCRIPTION OF THE INVENTION The amidine salts of this invention are obtained from a-amino nitriles by allowing the a-amino nitriles to react with methanol in the presence of a metal alkoxide to form an imidoether. The intermediate imidoether is then allowed to react with an ammonium salt in methanol to form the desired amidine salt.

The amidine salts of this invention are useful as stabilizers for polyesters, and the imidoethers of this invention are useful in the preparation of such amidine salts.

In the polyester art and polyester preparation art the term stzibilizef has come to mean an additive which is effective in retarding or preventing polymerization of premixed polyester compositions prior to molding but which is substantially without effect upon polymerization under the conditions prevailing during molding where a catalyzed polyester composition is subjected to elevated temperatures such temperatures being well in excess of normal room temperatures of about 20 30 C. An inhibitor differs from a stabilizer primarily in that the inhibitor retards or prevents polymerization at normal room temperatures and at the elevated temperatures generally used in molding polyesters. In other words, stabilizers are effective in preventing or retarding the polymerization or premixed polyester compositions where such compositions are stored at about normal room temperature without substantially retarding the catalyzed polymerization of such compositions under molding conditions (i.e., under elevated temperatures).

We have found that the imidoethers and amidine salts of this invention can be prepared from nitriles by a sequence of reactions represented by the following equations j (where R is CH; (CH,) C H or CH and X is Cl or Br):

lHllgUNll (imidouther) lNILX (amidine salt.)

Where using nitrilotriacetonitrile as the 'nitrile'the sequence of reactions is represented by the following equations (where X is Cl or Br):

iCllgONll (N-cyanomuthyl- I OCH:

Our invention is further illustrated by the following specific but nonlimiting examples.

EXAMPLE 1 (Preparation of N-Acetyliminodiacetonitrile) low melting solid, mp. about 36-37C.). The crude product was used in Example II, infra, for the preparation of an imidoether and an amidine salt.

EXAMPLE II (Preparation of N-acetyl-N-carboxamidinemethylglycinonitrile-hydrochloride) Crude N-acetyliminodiacetonitrile (79 g, 0.57 mole) was added to a solution of sodium methoxide (2.7 g, 0.057 mole) in 300 ml. anhydrousmethanol in a 1 liter flask fitted with a stirrer, thermometer, and drying tube. The clear reaction mixture was stirred at room temperature for 2 hours. After standing overnight, the solid present was collected by filtration and air-dried. More solid was obtained by evaporation of the filtrate. A total of 54.5 g (corresponding to a yield of 57 percent of theory) of crude imidoether was obtained. This material was identified by its infrared spectrum as N- acetyl-N-(Z-methyl acetimidate)-glycinonitrile.

The crude imidoether (20.6 g) was placed in a 250 ml. flask fitted with a stirrer, thermometer, and drying tube. Anhydrous methanol, 75 ml., was added and most of the solid dissolved. Ammonium chloride (7.0 g, 0.13 mole) was added on one portion. The reaction mixture was stirred for 2.5 hours, during which time a precipitate formed. After standing overnight, a pale yellow solid product was observed. This solid product was collected by filtration. It was washed with cold methanol, and air-dried. The product, which was identified as N-acetyl-N-carboxamidinemethylglycinonitrile-hydrochloride,

o o HZCN I o II3C-N oH, =N1-t-1-t01 N1 1:

by its infrared spectrum and comparison of this spectrum with those of the other amidine salts described, weighed 15.7 g. (corresponding to a yield of 68 percent of theory).

EXAMPLE III (Preparation of N-lauroyl-N-carboxamidinemethylglycinonitrile hydrochloride) In a 1 liter flask fitted with a stirrer, thermometer, and drying tube was placed 109 g (0.39 mole) of N-lauroyliminodiacetonitrile, 2 g (0.04 mole) of sodium methoxide, and 500 ml. (ca. 12 moles) of anhydrous methanol. After stirring for approximately 20 minutes, all the solid dissolved. The clear, orange-yellow solution was stirred an additional 4.5 hours at room temperature. After standing overnight, a pale yellow solid was present. The solid was collected (by filtration) washed with ether and air-dried. Additional solid was recovered from the filtrate by evaporation. A total of 114 g (correspondingto a yield of 94 percent of theory) of crude imidoether was obtained. This imidoether was identified as N-lauroyl-N-(2-methyl acetimidate)-glycinonitrile, by infrared and the determination of its equivalent weight. Titration of this sam: ple with alcoholic HCl gave an equivalent weight of 322. The crude imidoether melted at ca. 88-93C. and softened at 87C.

Ammonium chloride (2.7 g; 0.05 mole) was added with stirring to a slurry of 15.5 g of the crude imidoether in ml. of methyl alcohol. Solid was present throughout the stirring period (2 hours), and took on a silky-like appearance. The fluffy-white solid was collected, washed with ether and air-dried to give 14.7 g (corresponding to a yield of 88 percent of theory) of crude product. This material did not melt up to 210, but shrank and became progressively darker. The analyical sample was re-crystallized from hot methanol. The crude product (3.0 g) was dissolved in 60 cc hot methanol and filtered. After standing overnight, the solid was collected, washed and dried to give 1.4 g (47 percent) of dry material. This material was identified as glycinonitrile hydrochloride by elemental analysisand by its infrared spectrum. The elemental analysis was Calculated, fOf C gH31N ClO: %N=I6.93;%Cl=10.71 j Found:58.22; 9.42; 17.05; 10.78 corresponding to the formula EXAMPLE 1v (Preparation of N-be'nzolyl-N-carboxamidinemethylglycinonitrile hydrobromide) In a liter flask fitted with a stirrer, thermometer, and drying tube was placed 300 ml. of anhydrous methanol and v2 g (0.04 mole) of sodium methoxide. N- benzolyliminodiacetonitrile (79.6 g; 0.4 mole) was added and dissolved after stirring 15 minutes at room temperature. After stirring 7 hours and standing overnight, a yellowish solid was present. This was collected by centrifugation and air-dried. More solid was recovered by evaporation of the mother liquor. A total of 69.0 g (corresponding to a yield of 75 percent of theory) of crude imidoether was obtained. This material was a yellow-tan solid which showed no definite melting point; the material darkened on heating and began to decompose at approximately Titration of the crude product gave an equivalent weight of 253. This material was identified as N-benzoyl-N-(Z-methyl acetimidate)-glycino-nitrile by infrared and the determination of its equivalent weight.

N-lauroyl-N-carboxamidinemethylo CIIQCN EXAMPLE V (Preparation of N-cyanomethyl-nitrilodiacetamide dihydrobromide) Nitrilotriacetonitrile (26.8 g; 0.2 mole) and sodium methoxide (0.02 mole) was stirred in 225 ml. methanol for 7 hours and allowed to stand overnight. Addition of ammonium bromide (59 g; 0.6 mole) with stirring caused precipitation of a light tan solid. The reaction mixture was stirred an additional 2.5 hours, and the solid was then collected and dried, to give 59.2 g (89.5 percent) of N-cyanomethyl-nitrilodiacetamidine dihydrobromide. The product was identified by elemental analysis and by infrared spectrum.

Since the product was shown to have the dramldine structure,

No-ouz- N--((:1| :Nll) mun- Nll the intermediate imidoether was similarly identified as the diimidoether,

N-cyanomethyl-nitrilodi-2-methylacetimidate.

What is claimed is: 1. An imidoether having the formula o omcN C5H5C-N CH:C=NH

( )CHa 2. A process for preparing an imidoether having the formula l (min comprising:

a. forming a product mixture consisting essentially of the imidoether, methanol, and sodium methoxide by contacting and reacting at about 0-30C. methanol with a nitrile having the formula in the presence of a catalytic quantity of sodium methoxide, the mole ratio of the nitrile to the methanol being about 1:15-30, the mole ratio of the sodium methoxide to the nitrile being about 1:10-50, and the contact time being about 4-105 hours;

b. separating the imidoether from the methanol and sodium methoxide components of the product mixture; and

c. recovering the separated imidoether.

3. An amidine salt having the formula wherein X is an ion selected from the group consisting of chloride and bromide.

4. A process for preparing an amidine salt having the formula wherein X is a member selected from the group consisting of Cl and Br, comprising:

a. forminga product mixture consisting essentially of the amidine salt and methanol by contacting and reacting at about 25-30C. an imidoether having the formula with an ammonium salt having the formula NH X, wherein X is a member selected from the group consisting of Cl and Br in the presence of methanol, the mole ratio of imidoether to methanol being about 1:20-60; the mole ratio of imidoether to ammonium salt being about 1:1-2, and the contact time being about 1-20 hours;

separating the amidine salt from the methanol; and c. recovering the separated amidine salt.

1: v w I s s 

2. A process for preparing an imidoether having the formula
 3. An amidine salt having the formula
 4. A process for preparing an amidine salt having the formula 